Rotor, in particular a helicopter rotor

Abstract

A rotor, in particular a helicopter rotor, whereby the movement of the pitch angle of the rotor blade relative to a rotor hub is provided either by a blade neck with torsional flexibility disposed between a blade root and a blade wing or by a blade connection on a rotor hub arm with torsional flexibility. The pitch angle control for the blade is provided by a steering rod coupled to a torsionally stiff blade control casing extending coaxially without making contact along the blade neck or the rotor hub arm up to the blade wing or to the blade root. The control casing is supported on the blade root or rotor hub by at least one brace, which brace, in the longitudinal direction of the blade, has a T-shape. The vertical section of the T-shape is coupled to the blade control casing and the T-base is coupled with torsional flexibility to the blade root or the rotor hub arm, whereby the connection to the base is limited to both of the extremities of the base. Thus, the brace provides both a supporting function for the blade control casing and acts as a torsion bearing that enables rotational movement of the blade control casing and thus change of the blade pitch angle.

What is claimed is: 
     
       1. A helicopter rotor comprising a rotor blade coupled to a rotor hub, the rotor blade having a blade root portion coupled to the hub, a torsionally flexible blade neck portion and a blade wing portion, the blade neck portion being disposed between the blade root portion and the blade wing portion, the rotor comprising a torsionally stiff blade control casing extending coaxially about the blade neck portion between the blade root portion of the rotor blade and the blade wing portion, said control casing not making contact with said rotor blade along the neck portion of the blade and being coupled to the blade wing portion, said rotor further comprising means for controlling the pitch angle of the rotor blade relative to the rotor hub, said means for controlling the pitch angle comprising a steering rod coupled to said control casing, said control casing being braced at the blade root portion by a brace, said brace comprising a T-shaped element extending between said blade root portion and said control casing, said T-shaped element having a substantially horizontal member and a substantially vertical member and being disposed such that the substantially horizontal member is adjacent the blade root portion, said substantially horizontal member having brackets at ends thereof fixed to said blade root portion, said substantially vertical member having at an end thereof adjacent the control casing a bracket fixed to said control casing, said substantially horizontal member of said T-shaped element being torsionally flexible, said brace being coupled to said rotor blade root portion only by said brackets at the ends of said substantially horizontal member. 
     
     
       2. The rotor recited in claim 1, wherein a width of the substantially horizontal member of the T-shaped element is greater than the height of said substantially vertical member of said T-shaped element. 
     
     
       3. The rotor recited in claim 1, wherein the brace comprises at least two T-shaped elements having torsional and bending flexibility assembled between said control casing and said rotor blade root portion having a V profile in cross-section, the V profile being symmetrical relative to the plane of the rotor blade, the V profile having a root coupled to the blade root portion with a distance between the T-shaped elements at the root such that axes of the T-shaped elements intersect in a longitudinal axis of the blade. 
     
     
       4. The rotor recited in claim 3, wherein the T-shaped elements comprise flat springs made of fiber reinforced plastic. 
     
     
       5. The rotor recited in claim 3, wherein the brackets of the T-shaped elements are coupled together by a further fixing bracket, a fixing bracket being disposed between said brackets at ends of the substantially horizontal members and said rotor blade neck portion and between said brackets at ends of the substantially vertical members and said control casing. 
     
     
       6. A helicopter rotor comprising a rotor blade coupled to a rotor hub, the rotor hub having a torsionally flexible hub arm, the rotor blade having a blade root portion coupled to the hub arm, the rotor comprising a torsionally stiff blade control casing extending coaxially along the hub arm to the blade root portion, said control casing not making contact with said hub arm and being coupled to the blade root portion, said rotor further comprising means for controlling the pitch angle of the rotor blade relative to the rotor hub, said means for controlling the pitch angle comprising a steering rod coupled to said control casing, said control casing being braced at the hub arm by a brace, said brace comprising a T-shaped element extending between said hub arm and said control casing, said T-shaped element having a substantially horizontal member and a substantially vertical member and being disposed such that the substantially horizontal member is adjacent the hub arm, said substantially horizontal member having brackets at ends thereof fixed to said hub arm, said substantially vertical member having at an end thereof adjacent the control casing a bracket fixed to said control casing, said substantially horizontal member of said T-shaped element being torsionally flexible, said brace being coupled to said hub arm only by said brackets at the ends of said substantially horizontal member. 
     
     
       7. The rotor recited in claim 6, wherein a width of the substantially horizontal member of the T-shaped element is greater than the height of said substantially vertical member of said T-shaped element. 
     
     
       8. The rotor recited in claim 6, wherein the brace comprises at least two T-shaped elements having torsional and bending flexibility assembled between said control casing and said hub arm to form a V profile in cross-section, the V profile being symmetrical relative to the plane of the rotor blade, the V profile having a root coupled to the hub arm with a distance between the T-shaped elements at the root such that axes of the T-shaped elements intersect in a longitudinal axis of the blade. 
     
     
       9. The rotor recited in claim 8, wherein the T-shaped elements comprise flat springs made of fiber reinforced plastic. 
     
     
       10. The rotor recited in claim 8, wherein the brackets of the T-shaped element are coupled together by a further fixing bracket, a fixing bracket being disposed between said brackets at ends of the substantially horizontal members and said hub arm and between said brackets at ends of the substantially vertical members and said control casing.